The present invention relates to an improved connecting mechanism which can be weight set for securing one tubular member within another in a preloaded condition within a subsea well.
Prior to the present invention the securing of one tubular member within another member in a subsea well involved the use of a pressure responsive actuator which moved a wedge or other shape into position to urge the latching mechanism into engagement within the internal profile of the outer tubular member. An example of this type of pressure responsive connecting structure is shown in U.S. Pat. No. 4,372,584 wherein abutting tubular members are connected by locking fingers of a locking sleeve. One end of the fingers is engaged in the flange of one tubular member and the other end is wedged outwardly into engagement with an internal flange on a sleeve extending from the other tubular member into surrounding relationship with the flanged end of the first tubular member. The locking fingers are wedged outwardly by a wedge sliding on the exterior of the first tubular member and move responsive to hydraulic pressure supplied to a fluid chamber defined between a ring secured to the first tubular member and the interior of the wedge. This disclosure does not suggest a connection in a subsea well but such connections do utilize hydraulically actuated wedges to force the locking element into the interior profile of the outer member. The R. L. Crain U.S. Pat. No. 3,489,221 is an example of such structure with the split ring being held in a recess on the exterior of the inner member and then released to move into the interior profile of the outer member and has a tapered surface to wedge it or lock it into such engagement to support the inner member from the outer member.
U.S. Pat. No. 4,355,825 discloses a mudline suspension system in which a split ring having slots cut vertically from the top and bottom is adapted to engage a shoulder on the interior of the exterior member and to have the interior member landed thereon. Another similarly designed ring is disclosed in U.S. Pat. Nos. 4,534,583 and 4,509,594. Both of these structures provide the ring to be interposed between the two members when landed.
U.S. Pat. No. 4,697,828 discloses a preloaded connection for a subsea well in which the inner member carries a lock ring and a wedging ring. The lock ring includes an upper outwardly extending flange which engages the top of the outer member and the lock ring also has a lower outwardly extending projection which is adapted to engage within an internal recess in the outer member. The wedging ring surrounds the inner tubular member and engages a downwardly facing flange thereon and is partially within the lock ring during lowering. Once landed the wedging ring is forced downwardly by a separate hydraulic tool to a position within the lock ring and causes its lower projection to be wedged into engagement within the outer member recess to provide a preloaded locked connection between the two members.
U.S. Pat. No. 4,651,830 discloses a latching connection for a wellhead housing within a conductor casing in a subsea wellhead in which a split latching and loading ring is set by downward movement of a wedge or cam into an internal groove in the conductor casing. A retrievable hydraulic actuator is used to move the wedging ring. The split ring transmits the load between the housing and the conductor casing and also latches them together to retain the housing on the seat within the conductor casing.